JSON Formatter & Validator
Format, validate and minify JSON instantly — 100% in your browser.
About JSON Formatter & Validator
Paste your JSON below and it is instantly parsed, validated and pretty-printed. If the JSON is invalid, you get the exact error and position so you can fix it fast.
Everything runs locally in your browser using the native JSON parser — your data is never sent to a server, which makes it safe for API responses, config files and other sensitive payloads.
How to use JSON Formatter
- Paste a complete JSON value or load the sample; syntax errors appear as you type.
- Choose Text, Tree or Compact output. Text supports 2, 3, 4 or 8 spaces and tabs; Tree lets you expand nested objects before copying the result.
Limitations and common mistakes
JSON requires double-quoted keys and strings. Comments, trailing commas and JavaScript expressions are not valid JSON; formatting does not repair their meaning.
Numbers are parsed with JavaScript number precision. Integers beyond the safe range can change value; represent identifiers as strings. Very large documents may slow the browser.
The tool processes its input locally on your device. Read our privacy policy for analytics, storage and network details.
Format compact JSON
{"name":"Ada","langs":["en","fr"],"active":true}{
"name": "Ada",
"langs": [
"en",
"fr"
],
"active": true
}Choose Text view with 2, 3, 4 or 8 spaces or tabs, Tree view to explore collapsible nodes, or Compact view to minify JSON.
Frequently asked questions
Is my JSON uploaded to a server?
No. Parsing and formatting happen entirely in your browser, so your data never leaves your device.
What does the validator check?
It uses the browser's native JSON parser, so it flags any syntax that isn't valid JSON — trailing commas, unquoted keys, single quotes, and so on — with the error message and location.
Can it minify JSON too?
Yes. Choose Compact in the View menu to remove all insignificant whitespace and produce the smallest valid JSON output.
For related tasks, explore JSONPath Evaluator and JSON to Code. Their guides explain the different inputs, assumptions and output formats.